Abstract: objective To observe serum urokinase level and calcium in kidney stone patients and analysis the relevance. Methods 27 patients with calculus (stone group) and 24 healthy crowd (control group) were divided into two groups, serum urokinase level of all research object were measured by enzyme-linked immuno sorbent assay(ELISA), serum calcium level was test by biochemical detection, at the same time test renal function (serum creatinine). Results The serum urokinase level with stone group was lower than control group (P < 0.001), calcium level was higher than control group (P < 0.01); The change of of urokinase level and calcium level of stone group was negatively correlated(P < 0.01), the change of urokinase and creatinine level was negatively correlated too(P < 0.05). Conclusion The Serum urokinase level of healthy crowd was higher than patients with stone, and the urokinase may be as a new inhibitor restrain the process of stone formation by protecting renal function and reducing calcium levels.